Chapter 4: Lateral Placement and HeightAnchor: #i999730
Section 1: OverviewAnchor: #i999736
The lateral placement and height of signs affect both the operational and safety performance of signs. Signs that are too far from the edge of the road or too high may not be in the drivers’ cone of vision. Furthermore, they may not be able to retroreflect sufficient light at night to be legible to drivers. Signs that are too close to the edge of the travel way may have a higher probability of being hit by vehicles leaving the travel way.
This chapter illustrates the principles for the distance that signs should be placed from the edge of the travel lane or shoulder and how high signs should be placed above the roadway or ground. Several different figures provide illustrations of different situations that can affect the lateral placement of signs or sign height.Anchor: #i999751
Terminology Used in the Field Book
Figure 4-1 illustrates how the following terms are used throughout the field book. It also identifies the point of reference from which to measure the lateral offset. Part 1 of the Texas MUTCD contains additional definitions.
- Traveled Way: The portion of roadway for the movement of vehicles, exclusive of the shoulders, berms, sidewalks, and parking lanes.
- Shoulder: For determining the lateral offset of a sign, it is the paved portion of the highway that is outside the traveled way.
- Front slope: The portion of the ditch that is on the road side of the flow line.
- Ditch: An area centered on a flow line that is intended to drain water.
- Back slope: The portion of the ditch that is on the opposite side of the flow line from the road.
- Edge of travel lane: If an edge line
is present, it is measured from the outside edge of the edge line.
If there is no edge line, it is measured from the edge of pavement.
Figure 4-1. Illustration of Terminology